Predicting the nation's weather
just got a boost because of a new weather computer model that
has just become operational, according to the Commerce Department's
National Oceanic and Atmospheric Administration (NOAA).
The model improves the accuracy and timeliness of short-range
weather forecasts, particularly for the aviation community and
for the general public.

The Rapid Update Cycle (RUC20)
model was developed at NOAA's Forecast Systems Laboratory (FSL) in Boulder, Colo., and
funded by NOAA and the Federal Aviation Administration (FAA)
Aviation Weather Research Program. Called the RUC20 because of
its 20-km resolution, it improves forecasts widely used for aviation,
severe-weather forecasting, and general weather forecasting.

"The Storm Prediction Center
uses the RUC model extensively in its severe weather forecast
operations," said Joe Schaefer, director of NOAA's
Storm Prediction Center in Norman, Okla. "Operational
computer model advances like this made possible by the advanced
capabilities of the new National Weather Service supercomputer
promise to advance our skill in forecasting tornadoes and other
forms of hazardous weather to protect the American public."

The model was implemented on
April 17 at the National Centers for Environmental Prediction
(NCEP) in Camp Springs,
Md., part of NOAA's National
Weather Service (NWS). Using the latest observations from
commercial aircraft, wind profilers, satellites, radars, weather
balloons, and surface stations, the RUC20 produces new analyses
and short-range forecasts on an hourly basis, with forecasts
out to 12 hours every three hours, the highest-frequency updating
of any forecast model at NCEP.

"The RUC20 takes another
step forward toward representing the complexity of real weather
and provides considerable improvement for short-range forecast
users," said Stan Benjamin, manager of the RUC project at
FSL.

The model covers the continental
United States and is run on a 20 km grid. The RUC20 is an improved
version of an earlier model. Featuring increased horizontal resolution
(from 40 km to 20 km) and more vertical levels (from 40 to 50),
the RUC20 improves the overall accuracy of weather data being
fed into aviation-weather and other weather applications. The
major improvements of the RUC20 over its predecessor are better
cloud and precipitation forecasts, and better wind and temperature
forecasts near the surface. The RUC20 also provides improved
forecasts of icing and turbulence conditions hazardous for aviation.

"Improved numerical forecast
models are extremely important to the prediction of potentially
hazardous weather conditions for aviation operations," said
Greg Burke, chief of the FAA's Office of Air Traffic Systems
Development. "The increased resolution of the RUC20 model
will help identify weather phenomena that were previously not
well defined."

The smaller grid spacing used
by the RUC20 provides better resolution of variations in land
elevation, land-water boundaries, and other land-surface features.
This detail leads to improved forecasts of regional and local
precipitation and surface wind phenomena. The RUC20 incorprates
satellite cloud data to improve its cloud, icing and precipitation
forecasts. It also handles convective and non-convective clouds
more effectively.

For aviation operations, the
RUC20 enhancements will result in better forecasts in the vicinity
of warm and cold fronts, where bad weather tends to concentrate,
including areas of potentially hazardous turbulence and icing,
and more accurate forecasts of surface winds, temperature, and
precipitation. RUC forecasts of jet-level winds and temperature,
critical for U.S. flight routing and air traffic management,
are also improved.

"Improvement in Aviation
Weather Center products due to RUC20 improvements over the current
RUC2 will enhance the en-route warning, forecast, and advisory
program serving the National Airspace System," said Jim
Henderson from NOAA's
Aviation Weather Center in Kansas City. "In an evaluation
of the experimental fields at the AWS, the forecast of both convective
and non-convective cloud tops showed a major improvement as did
the forecast of visibility fields. "

Computer modeling is central
to all NWS weather, flood, and climate forecasts. Throughout
the day, data are collected by a vast array of observing systems
such as the network of weather balloons, Doppler weather radars,
sensors on commercial aircraft, automated surface observing systems,
and advanced satellites. The data are processed through powerful
computer models run at NCEP's Maryland facility. The computers
generate predictions for forecasters, allowing them to anticipate
weather conditions from one hour to weeks and seasons in advance.
Of all the models running at NCEP, the RUC20 is designed for
the most immediate guidance  within the next 12 hours.

Among the many users of the model
are NOAA's Aviation Weather Center in Kansas City, Mo., NOAA's
Storm Prediction Center in Norman, Okla., National Weather Service
forecast offices, commercial airlines, and any users that need
immediate information on the state of the weather in the next
few hours.

The Commerce Department's National
Oceanic and Atmospheric Administration (NOAA) is dedicated to
enhancing security and national safety through the prediction
and research of weather and climate-related events and providing
environmental stewardship of our nation's coastal and marine
resources. To learn more about NOAA, please visit http://www.noaa.gov.

NOAA/FSL collaborated with NCEP
and the National Center for Atmospheric Research (NCAR) on development
of the RUC20.